A method of increasing recovery of liquid hydrocarbons from subsurface reservoirs, and particularly from those located in tight formations, is disclosed. One aspect includes calculating the in situ fractured formation wettability from real-time measurement of flowback volume and composition. Another aspect includes determining the composition of the fracturing fluid, the overflush or both, that will achieve higher liquid hydrocarbon recovery by increasing the water wettability of rock surfaces within the reservoir. Monitoring of rock-surface wettability through flowback volume and composition profiles allows the above mentioned injectates to be adjusted in the field to achieve maximal recovery. Other methods, apparatuses, and systems are disclosed.
Production of liquid hydrocarbons from reservoirs is controlled by natural forces, such as solution gas expansion and natural water drive, or by engineered forces during enhanced oil recovery (EOR), such as injection of steam, surfactants, solvents or CO2, or the creation of differential water pressures such as in a waterflood operation. Steam injection decreases liquid hydrocarbon viscosity. Surfactant injection decreases liquid hydrocarbon-water interfacial tension. CO2 injection simultaneously reduces liquid hydrocarbon-water interfacial tension and enhances formation pressure. Polymer injection is a physical EOR technique that improves waterflood sweep efficiency by blocking zones whereby water would otherwise bypass liquid hydrocarbons.
Primary liquid hydrocarbon recovery relies on natural forces; secondary and tertiary recovery rely on engineered forces. Traditionally, primary recovery is followed by secondary recovery (waterflooding), then tertiary recovery. The analysis described herein differs from the traditional approach to liquid hydrocarbon recovery because it develops an up-front understanding of the chemical forces that hold the liquid hydrocarbon in the particular reservoir to begin with, then uses that understanding to design an overall liquid hydrocarbon recovery strategy that maximizes recovery of liquid hydrocarbons.